Alkylation of hydrocarbons



March 1943- K. KORPl ETAL 2,436,965

ALKYLATION OF HYDROQARBONS Filed June 18-, 193? STABILIZER FRACTIONATOR- SET TLER NEUTRALIZER SEPARATOR KARL KORPI ARTHUR R.Gol.o BY INVENTOR lSO-PARAFFI ATTORNEY Patented Mar. 2,1948

uni-frenzy STATES PATENT OFFICE;

I abscissa AEKYLATIUN OF HYDROGARBONS Tex cassignors by mesne assignments, to The Texaacompany, New York, N. Y., a corporation of Delaware 'Applieationduric' 18, 1937;8erial No. 148;978"f 12' Claims; (01. 260;;683J4) This invention hasto do with. the. alkylation of hydrocarbons by the -tm-ion efparafilns olefinsr In particular the invention. is. concerned with the production: of motor-fuel hydrocarbons "f improvedantiknocle. value irom gaseous hydrocarbons by reacting i-so-paraffins-zwith clefi-ns in the presence c-a-catalyst..- 7

It is well known? inthe. art ethat-iaromatic hydrocarbons-such as benzene may be alkylated bycondensation witn'olefi-ns in the presence of a suitable catalyst.- This reaction apparently. is possible :becauseot. the. reactivity of the hydrogen atoms-inthebenzenermolec llea V Iso-paraflins contain hydrogenrattachedtoztertiary carbonv atomsnwhich .possessunusual=--reactivity and. in somecases even surpassthat. of the benzene hydrogen It has been. found tha t alkylationof iso-paraiiins .--may.. .beefiected- .by oleiins .under proper conditions and withsas suit.- able ..-catalyst., .Reactions! .of this type may .be symbolized. as follows, using lsobut'ane as theisoparaffinz 1 cna gc cnt+netom)a= (CHflsQ -GKGHQI owns);

(a) onr on -oaficnt-s 1 i o ?r, 0H)

CHS;CH23;TO (C oa 011 4' I CHPGHCH+HCCCHM"-- era-1on1: I

6 (CH3): 'lI'he above. type; ofreactions is. essentially'the union of an olefin with an iso-parafinito obtain .a higher molecular Jweight iso-paraflini- By reacting hydrocarbons of tneproper. molecular weight, it, possible'to obtain products of the gasoline boiling 'range andpossssing a lii'gh'antiknock value.

In waccordance;with .tnepresent invention, it is preferable'to utilizelhy'droaib'ons' containing about 4 carbon atomswhfebyla high yieldof products. of predominantly {8 carbon atoms. or octans isobtained. It been found,ior 'example, thati'by' reacting iso utane with a Cl unsaturated hydfccar'bonnaenon, a good yield of high antiknock' motor ruel may be obtained.

and

Although itis preferable to utilize the olefin stocksot about- 4 carbon atoms because a higher octane-product may be produced, .the process is applicable to, and. a; goodproduct. may be ob.- tained. from.- olefin: stocksof 3..carbon atoms... In some cases thismay be preferable due tothe larger quantities of propylene availablaand, also because a product .of lower .point is obtained. It hasflbeen found; for example, that by reacting isobutanewwith. propylene, a good yield of high antiknock motor fuel may be obtained.

Theprocess may .also beadapted to unsaturated hydrocarbon iractions "which are comprised mainlyof amixture of Cs and. C4 hydrocarbons. In some-casesthis process may be preferred to those in W-hicha fraction .ofpredominantly. either 3 or 4 carbon atoms are used, because of the larger quantities of combined C3 and C4 available, and also becausetheproduct has a distillation. range which requires little light blending stock" to make it suitable for aviation'fuel'.

The invention will be further understood from the" followingexamples of operations coming within the'scopeof the invention.

Example I Isobutaneand concentrated. sulfuric acid (66 1361 the ratio of about 3' parts by volume of isobutane to 2 partsof sulfuric acid were introduced into. a reaction vessel. The mixture was agltated-and during. aperiod of about 4 hours, 7 parts of a 04 stock, consisting of a' refinery cracked gas. containing about 3.3% C3, 14.5% isobutylene and 25.8% normal butylenes, 11% isobutane, .44% normal butane and 1.4% of C5 wereslowly added. The reaction was allowed to continue- 1% hours after the olefin stock. was charged ordinary'temperatures were used and suificlnt pressure to maintain the products in a liquid-state.- The unreacted gas was removed fronithe vessel by releasing the pressure and theiliquid products separated'from the acid.

The yield of butane-free product. was about 1.50%"b'y weight;- of the olefin charged. About 76% of theproductdistilledbelow 300 F., 17% from 300 400 F., and the remainder of 7% above 400 F. The. 400 end point naphtha. was stable, less than 2%. unsaturated and had an octane value 0188."

EwampleJI Sulfuric acid (66B.) and a C4 stock containing a mixture of about 2 parts of isobutane to 3 parts by volume of a C4 fraction of cracked gasesof substantially the composition given in from SOD-400 F. and the remainder of 6% above Example III Sulfuric acid (400 cc. of 66 B.) is charged into an iron reaction bomb. To .the agitated acid in the bomb is charged 362 g. of a mixture,

per minute for about 170 unit volumes of acid in the alkylation operation. In the other examples the rate of olefin feed per unit volume of acid is even less.

Further it will be observed with respect to Example I that the amount by weight of sulfuric acid catalyst in admixture with isoparaffin is in excessof the amount by weight of isoparafiin. This is also true in the case of Examples 11, III and IV.

Also it will be observed with respect to Example I that the rate of feed to the alkylation operation of olefin in units of volume per minute is less than about /au the minimum of units of volume of excess unreacted isoparafiin in the reacting mixture.

containing 32% propylene and 68% isobutane byweight, at a constant rate in 3 hours. The reaction is allowed to continue ten minutes with agitation. The unreacted gas is removed from the bomb by releasing the pressure and the liquid product is separated from the acid in a separatory funnel. The alkylation reaction took place at 85-95.F. and 60 to 80 poundspressure per square inch gauge,

The yield of butane free product is 166% by weight of the olefin charged. 70% of the product distills below 311 F., 21.4% from till-400 F. and the remainder of about 7.3% above 400 F.

The 311 E. P. cut has an. initial boilin point of 137 F., a 10% point .of 1'74, a 50% point of 197 F., a 90% point of 236 F. and an end point of 283 F. by A. S. T. M. distillation, contains less than 0.5% of unsaturation, and has a C. F, R. M. octane of 81.9.

Example IV Sulfuric acid (400 cc. of -66 B.) is charged into an iron reaction bomb. To the agitated acid in the'bomb is charged 37'? g. of a mixture, containing by weight 12.5% propylene, 13.7% C4 ole fin, 38.4% isobutane and the majority of the remainder n-butane, at a constant rate in 3 hours. The reaction is allowed to continue ten minutes with agitation. The unreacted gas is removed from the bomb by releasing the pressure and the liquid product is separated from the acid in a separatory funnel. The alkylation reaction took place at 85-95? F. and 50 to 65 pounds pressure per square inch gauge.

The yield of butane free product is 120%. by weight of the olefin charged. 66.8% .of the product distills below 311 F., 22.4% from311-400 F., and the remainder of about 10.8% above 400 F.

The 311 F. cut was combined with the 311 F. cut of a similar run to obtain sufficient material for distillation and C. F. R. M. octane. Themixture has an initial boiling point of 112 F., a 10% point of 159 F., a 50% point of- 223 F., a 90% point of 268, and an end point of 300 F. by A. S. T. M.. distillation, contains less. than 0.5% unsaturation and has a C. F, R. M. octane of 81.

In Examples III and IV it will be observed that the time of contact of the reacting hydrocarbons in the presence of the sulfuric acid catalyst during the alkylation operation is from 10 minutes for the hydrocarbons last introduced to an average for all the hydrocarbons of about 100 minutes In Examples I'and II an even longer average time of contact is used.

Also it will be observed with respect to Example I above that the rate of olefin feed to the alkylation operation is less than 1 unit volume of olefin The process'may be operated either as a batch or continuous operation, but in general the continuous operation is preferable. In operating continuously, as hereinafter described, the isoparafiin and olefin hydrocarbons are fed simultaneously into the reaction zone containing the sulfuric acid catalyst, as is likewise true of the batch operations described in Examples III and IVabove, It is desirable to maintain the isoparaifin concentration quite high, for example at least in equivalent molar amount to the olefin concentration in the mixture, and in some instances from 2 to 3 times the olefin concentration. In continuous operation, it is advantageous to keep the initial reaction product between the acid and olefin low. The concentration of the initial products, probably the sulfuric acid esters, can be kept low by controlling the quantity of acid and the agitation.

The process has been operated successfully at temperatures of -90 F. and pressures of about 30-50 pounds. Lower temperatures from the above, of around 7580 F., are preferable but lower temperatures of down to zero or below may be used. It is desirable to maintain sufficient pressure to keep the materials in liquid phase.

The acid is strong sulfuric acid and preferably about 94 to concentration. The ratio of acid to oil may vary considerably. For an oil mixture containing about 20% olefins, for example, the amount of acid should be at least about 5% and may run as high as 100% by volume of the oil. In the specific examples set forth above the amounts of acid employed range from about 45% by volume of the oil in Example I to substantially higher proportions in the other examples.

It is unnecessary to use an unsaturated gas of any particular composition since substantially all the olefins react. Cracked gases of 30-40% olefin content are preferable although products containing from 5-50% or more unsaturation may be used. Typical C4 gaseous fractions, for example, run about 15% isobutylene, about 25% normal butylene, about 10-15% isobutane and about 45% normal butane.

While sulfuric. acid has been found to be a very satisfactory catalyst, it is contemplated that other catalysts, such as aluminum chloride and aluminum bromide, may be used. Y

In the accompanying drawing there is shown one form of apparatus for carrying out the continuous process of the invention, although other types of apparatus may be used.

Referring to the drawing, an unsaturated gaseous hydrocarbon fraction, such as a C4 fraction or a fraction of cracked gas containing a substantial, amount of or predominating in C4 hydrocarbons, is charged through the line I and "mixer 4; Isop'aramn hydrocarbons, such -isobutane, are charged through the line :5 and Pierced 'by the pump 6 through the line l also the mixer i. A catalyst such as sulfuric acid. as introduced through the line 10 and forced by the pump l'l through the line i2 into the mixer 4. The mixer may be any suitable mechanical means forag'itating or efiecting contact between the oil and the acid, suchas mechanical mixers, criflce plates, and the like. the mixer 4, it is intended that the acid-and hydrocarbons react to produce a union between the ol'e'fins and isoparaifins-to-eifect reactions of the nature of alkylation. The reaction products are; discharged from the mixer'lthrough the line 1 5, controlled by valve 16 to separator iii. 'In this separator the acid is separated and withdrawn from the bottom thereof through the line 2 3. This acid may be recirculated to the mix'er, if desired, by

m'eans of the line 21 and pump 22. 'The oil is withdrawn from the top of the separator through the line 24 and introducedv into the neutralize! 25. In this neutralizer the oil is contacted with a neutralizing agent, such as caustic or otherv alkaline material introduced through the line '28. The spent caustic, settling cutin theneutralize'r, is withdrawn from the bottom thereof through the line 2 8. This spent reagent may be recirculated, if desiredby means of the pump'ZB, located in the line 39. "The oil after contact with the neutralizing agent is conducted from the top of the neutralizingtower 25 through the line 32 and introduced into the settling toward-3, wherein any additional alkali is allowed to settle out and the latter iswithdrawnffrom the bottom of the tower through the line 35. This spent neutralizing agent also may be recirculated by means of the pump 35, located in the line 3:1. Fresh neutralizing agent, if desired, may be introduced through the line 38 in communication with line 31. The treated oil is withdrawn from the top of the settler 33,.throug'h the line and charged into fractionator 41 provided with a mean-s for heating in the lower portion thereof, such as heating coil 42. In this fractionator it is intended that a fraction of motor fuel boiling range be vaporized and taken overhead through the line 44 as a distillate fraction while material of higher boiling point than motor fuel is withdrawn from the bottom of the tractlonator through the line 451 Vapors are conducted through the line 44 to stabilizer 48 wherein the motor fuel hydrocarbons are --iractionated and separated from hydrocarbons of lower boiling point than motor fuel. The stabilized motor fuel product is withdrawn from the bottom of the stabilizer through the line 56 while the lighter materials comprising chiefly unreacted gaseous hydrocarbons are conducted from the top of the stabilizer through the vapor line 5! in which is located condenser 52. Condensate formed in the condenser 52 is passed to receiver 53 provided with a gas release line 54 and a liquid draw-off line 55. All or a portion of the condensate from the receiver 53 may be pumped as a reflux condensate by the pump 56 through the line 5? to the upper portion of the stabilizer. In some instances, such as where a molar excess of iso paraffin to olefin is present in the reaction zone, it may be of advantage to return to the system at least a part of the unreacted gases withdrawn through the gas release line 54, thereby serving to maintain this molar excess in continuous oporation. at leastiin partby: this external recycle as opposed to the fresh feed.

The feature of isoparailin olefin alkylation with strong sulfuric acid catalyst, wherein a substantial molar excess of isoparaffin to olefin is maintained throughout the entire reaction, is claimed in divisional application, Serial No. ceases, n'ow Patent No. 2,260,945, dated October 28', I941.

Obviously many modifications and variations oi the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated inthe appended claims; 7

1. Process ofalkylating is'o'p'araflins with olefins which comprises contacting isoparafiln and olefin with sulfuric acid of alkylating concentration, and maintaining a low concentration of alkyl ester initial reaction-product corresponding to a gasoline product of unsaturation below about 2%.

2. Process of making high antiknock motor fuel hydrocarbons which comprises catalytically al-kylating normally gaseous isoparainhs with normally gaseous olefins by means of sulfuric acid of alkyla'ting concentration as a catalysufand maintaining a low concentration of alkyl ester initial reaction product corresponding-to a gasoline product of unsaturation below about 2%.

3. Process "of reacting isobu'ta-ne with butylene toproduce iso-octanethereirom which comprises alkylating isobut'ane with butylenc -byc'ontact with sulfuric acid of alkylat-ing concentration, and maintaining a low concentration of alkyl ester initial reaction product corresponding to a motor fuel productof unsaturation below about 4. Process of reacting isoparafilns with olefins to form alkymers therefrom which comprises alkylating isoparaffin with olefin by contacting and agitating the isopara'iiln and olefin with sulfuric acid of alkylating concentration, and maintaining theconcentration of the alkyl ester initial reaction product suffi'ciently' low, to produce a motor fuel product of unsaturation below-about to produce aliz'ymei's therefrom which comprises alkylating fisoparafiin with olefin by contacting and agitating isoparafiin and olefin with sulfuric acid of alky-lating concentration, and maintaining a low concentration of alkyl ester initial reaction product to produce a good quality product of unsaturation below about 2% byicontrolling 0 the ratio of olefin to sulfuric acid. 6

,6. A process for the alkylation of hydrocarbons', which comprises maintaining a circulating stream of strong sulfuric acid in a closed circuit,

introducing into said stream an olefin and a low-boiling isoparaflin in such amounts that a molar excess of isoparaffin to olefin is maintained in the mixture and alkylating conditions are maintained, whereby isoparaflin is alkylated by the olefin, withdrawing reaction products from said stream and separating from the products withdrawn the alkylated hydrocarbons.

7. A process for the alkylation of a 1ow-boiling isoparaihn with an olefin, which comprises maintaining a circulating stream of strong sulfuric acid in a closed circuit, introducing into said stream an olefin and isobutane in such amounts that a'molar excess of isobutane to olefin is maintained in the mixture and alkylation conditions are maintained, whereby isobutane is alkylated by the olefin, withdrawing reaction products from said stream and separating from the products withdrawn the alkylated hydrocarbons.

8. A process for the alkylation of a low-boiling isoparaffin with an olefin, which comprises maintaining a circulating stream of strong sulfuric acid in a closed circuit including a reaction zone and a settling zone, continuously introducing into said stream in the reaction zone an olefin and a low-boiling isoparafiin in such amounts that a molar excess of isoparafiin to olefin is maintained in the mixture and alkylating conditions are.

maintained, whereby isoparaflin is alkylated with the olefin and hydrocarbon reaction products pass with the acid in said circulating stream to the said settling zone where the mixture stratifies into a hydrocarbon layer and an acid layer, continuously removing hydrocarbon reaction products from the hydrocarbon layer, and separating alkylated hydrocarbons from the products so withdrawn. v

9. A process for the alkylation of a low-boiling isoparaflin with an olefin, which comprises maintaining a circulating stream of strong sulfuric acid in a closed circuit, introducing into said stream an olefin containing C4 fraction and isobutane in such amounts that the isobutane is in isobutane with low-boiling olefins for the produc-- tion of normally liquid hydrocarbons within the gasoline boiling range, which comprises maintaining a body of reaction mixture including hydrocarbons in liquid phase and strong sulfuric acid of alkylation strength in a reaction zone under alkylating conditions, continuously introducing into the body of reaction mixture in the reaction zone a fresh charge comprising isobutane and a low-boiling olefin with the isobutane in molar excess of the olefin to effect alkylation of isobutane with the olefin, continuously withdrawing reaction mixture from said zone, separating the withdrawn reaction mixture into an acid layer and a hydrocarbon layer, recycling at least a portion of the separated acid layer to the reaction zone, continuously separating from the hydrocarbon layer a fraction of lower boiling point than motor fuel comprising unreacted gases, and recycling at least a part of said unreacted gases to said reaction zone, whereby the,

isobutane is maintained throughout the reaction in substantial molar excess or the olefin in said reaction zone.

I mixture including hydrocarbons in liquid phase and an alkylation catalyst in a reaction zone under alkylating conditions, continuously introducing into the agitated liquid body of reaction .mixture in the reaction zone a charge comprising the low-boiling-isoparafiin and the olefin with the isoparafiin in molar excess of the olefin to effect alkylation of isoparafiin with the olefin, continuously withdrawing a stream of reaction mixture from the maintained agitated bodyin said reaction zone, continuously separating the withdrawn stream into a, hydrocarbon phase and a catalyst phase, recycling at least a portion of the separated catalyst phase to the reaction zone, continuously withdrawing a stream of the separated hydrocarbon phase and fractionating the same to recover an alkylate within the gasoline boiling range and a lighter fraction including unreacted hydrocarbons of lower boiling range than the said alkylate, and continuously recycyling at least a portion of said unreacted hydrocarbons to said reaction zone. 1

12. A continuous process for the alkylation of a low-boiling isoparaflin with an olefin for the production of normally liquid hydrocarbons products from saidstream and separating from the products withdrawn an alkylate fraction within the gasoline boiling range.

KARL KORPI.

ARTHUR R. GOLDSBY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,001,906 Ipatieff May 21, 1935 2,002,394 Frey May 21, 1935 2,169,809 Morrell Aug. 15, 1939 2,260,945 Korpi et al Oct. 28, 1941 2,283,603 Goldsby et a1 May 19, 1942 OTHER REFERENCES J. A. C. 8., pages 1616-1621, Sept, 1935. 

